2.8 Timeline frame jump hotkey
You can add the missing hotkeys in the Preferences Panel.


Open Edit > Preferences, then click Keymap.
Click Add New.
Expand the panel and replace none with screen.frame_offset.
Set the Delta value (keyframes): 10 or -10
Click the default hotkey A and type your hotkey Up Arrow
Select the Modifier (Shift)

Save your preferences (if Auto Save Preferences is not selected)




Thanks to Zino.G, who answered this question on BlenderArtist: 
https://blenderartists.org/t/frame-jumping-in-2-8/1156440